Exchange's AutoMapping feature allows shared mailboxes to be added automatically to a user's Outlook if that user obtains full access permissions to that mailbox. This eliminates the need for the user to add the mailbox manually in Outlook. Subsequently, the same mechanism is also used when access to a shared mailbox is removed for a particular user. The mailbox should then automatically disappear from Outlook. Unfortunately, this does not always work properly.

Because of an intermittent bug, sometimes it can occur that a shared mailbox is not automatically removed from Outlook after access to that mailbox has been revoked. In fact, manually removing the mailbox (through Registry) doesn't help, and the mailbox gets placed back in Outlook after a few minutes.

Cause

The reason for this is that a certain attribute of the shared mailbox still contains a reference to the user's account, causing Exchange to place the mailbox back, even though the user has been denied access to the shared mailbox.

Resolution

You can manually remove the reference to the user account in the attribute of the account of the shared mailbox in Active Directory, using ADSI Edit.

1. Log on to a domain controller or management server with ADSI Edit using an account with Domain Admin rights.
2. Start up ADSI Edit (Start → Run: adsiedit.msc).
   Connect to AD and to the Default Naming context.
3. Navigate to the OU containing the AD account of the shared mailbox.
4. In the OU, right-click the object (CN=Shared Mailbox), and choose Properties to display the list of attributes for the account.
5. Locate and select the attribute msExchDelegateListLink, then click Edit.
6. A list of accounts is displayed. Accounts in the list have access to the shared mailbox and get the mailbox automatically added to Outlook. Not all users are necessarily in this list: if a full access permissions was set for a user with AutoMapping explicitly disabled, that user's account will not be in this list.
   Select the account of the user who needs the shared mailbox removed in his/her Outlook, then click Remove. Click OK to save changes to AD.

   Caution

   Be careful not to touch any of the other entries as they could lose access to the mailbox in their Outlook if they are accidentally removed.

7. Have the user restart Outlook. The shared mailbox will disappear after a few minutes.